Leading to the End
by Lets Do That Again
Summary: W.D. Gaster always considered himself a calm, cool, collected skeleton. Then the breaks in Time and Space occured.


Leading to the End

 **Toby Fox owns Undertale and all affiliated characters.**

"Talking"

" _Thoughts"_

 **Line Break**

W.D. Gaster woke with a start. He lazily swept his gaze around the room, taking note of the loose papers and odd piece of scrap lying haphazardly on his desk. One of his floating hands rubbed the back of his neck, _"Hmmm, I fell asleep while working again,"_ he chuckled wryly, _"Papyrus will have a fit if he finds out"_.

Gaster frowned when his phone rang. He flipped it open, "Who is it?"

"G-good morning professor Gaster".

Gaster smiled tiredly, "Good morning Alphys. How are you doing today?"

"Oh! J-just fine…I, I was wondering sir, about the DETERMINAT-"

Gaster suppressed a growl, "For the last time Alphys, those experiments were failures. I don't care what Asgore says, I'm not wasting anymore time chasing wild fantasies".

"Oh…" Alphys responded despondently, "o-of course…Anyway, I was hoping to give Mettaton a new exoskeleton," she started to ramble on and on about the various features the ghost would gain in the new suit. She stopped however, and Gaster could hear her embarrassed smile, "Um…why don't I just show you the blueprints?"

Gaster nodded his head, "Sure, sure…I need to go and check on the Core first and foremost though, ensure everything's running smoothly, you know, standard procedure".

"Y-yes sir, do you want me to come assist you?"

"No," one of his hands grabbed his coat, "you…why don't you take the day off".

Alphys was shocked, "A-are you sure sir?"

He stood up, smoothing out his jacket as he put it on, "Yes, you've seemed stressed over the last few weeks anyhow".

"Al-all right sir, h-have a good day!" She said, a littler more cheerful.

Gaster closed the phone with a smile. He strode out the door, a small smile on his face. Today was looking like a good one.

 **Line Break**

"Hello mister!"

Flowey plastered a smile on his face, "Howdy!"

The Froggit hopped closer, "You look lost".

Flowey nodded, he'd been wondering what to do during is run. Last time, he spent what seemed like days memorizing the last two seasons of Mettaton's program Word. For. Word. Before he met the Froggit, he was just milling around the ruins, mumbling inane catchphrases.

"If you want, you can come and stay with me and my family for a bit".

Flowey frowned contemplatively; he'd never done that before. "All right friend," he said, "Let's go!"

 **Line Break**

"Hey there Gaster!" Gerson waved.

Gaster waved back, moving closer to the old turtle, "Hello Gerson, how are you doing today?"

"Oh, pretty well," he craned his neck, "Just going over to meet Undyne, you know, the girl I've been telling you about?"

"Ah yes," Gaster nodded, "She is applying for the position of head of the Royal Guard, no?"

Gerson nodded, smiling widely, "Yes sir, and she's a real catch, be of great help to Asgore…Lord knows he needs it". Gerson added sadly.

Gaster sighed. He swept his gaze side-to-side. No one else but them, "Yes…I think he's starting to regret his decree".

Gerson frowned, "I'd hope so…Toriel still hasn't left the ruins, huh?"

Gaster smirked mirthlessly, "Hmph, she's been there so long, I think more than a few monsters have forgotten that Asgore had a wife".

Gerson sighed deeply, "…It really is a shame what happened to those two children…still, can't say I blame Asgore for what he's done".

Gaster looked down, "…No, I can't either". He turned his head toward Gerson, "Well, as…nostalgic…this has been, I must get going".

Gerson waved his hand, "Of course, don't want to keep you from your duties. Have a good day".

 **Line Break**

The front door of the Froggit household opened, "I'm home!"

"Dad!" the Froggits surrounding Flowey (who was doing his best not to look bored out of his mind) hopped towards their father.

The eldest said, "I thought you said you'd be coming home late?"

The father smirked, "The spiders were particularly generous today, gave me a whole load of flies…you know what that means".

"Fly soup!"

Flowey rolled his eyes, "Joy…"

 **Line Break**

Gaster frowned as he from one screen to the next, his extra hands typing at astonishing rates. _"Hmm…it looks stable, it feels stable, but something is…off"_.

He rubbed his chin, _"…I should take a look inside, just to be safe"._

He teleported to a large machine at the end of the room. He punched in the access code, stepped inside when it opened, and started to type in the various parameters and countermeasures necessary to ensure a safe trip into the core.

 **Line Break**

Flowey sighed, _"This got stale fast"._ He looked down with disgust at the fly soup the Froggits served him. _"I wonder…what if the father…didn't bring home the flies?"_ He shifted his gaze to the side, and a large button with the word RESET came into being. Lazily, he slapped it with a vine.

 **Line Break**

W.D. Gaster woke with a start. He lazily swept his gaze around the room, taking note of the loose of papers and odd piece of scrap lying haphazardly on his…desk.

Gaster jolted upward, frantically looking around the room. _"What in the…I thought for sure I was down at the Core…in the Core…was I dreaming?"_ He shook his head, scoffing, " _No…I must have finished later than I thought…yes that's it"._

He flinched slightly when his phone rang. The ringing pounded in his skull, "H-hello?"

"G-good morning professor Gaster".

Gaster sighed, "…Good morning Alphys".

There was a pregnant pause, "Sir…I, I was wondering sir, about the DETERMINATION EXPERIMENTS-"

"Alphys," Gaster cut her off, "Didn't we talk about this yesterday? I already told you, let it go," he leafed through the papers on his desk, "…and I thought I asked you for those blueprints on Mettaton's new exoskeleton?"

Alphys gasped slightly, "Professor…H-have you been going through my work station? I never mentioned Mettaton's new exoskeleton".

Gaster froze, "…That's impossible. Alphys you talked all about it. How Mettaton would receive all sorts of offensive upgrades, and you compared him directly to one of you silly little animate programs, Meow something".

"P-professor…I h-haven't mentioned that to a-anyone".

Gaster rubbed his temples, "You know what, forget it…just forget everything I said…you have the day off," Gaster unceremoniously closed the phone.

He sat down. He looked down at his desk, deciding to tidy up a bit, in an effort to forget this strange feeling. It did not work, _"Maybe I was too close to the Core? But surely I would have already discovered—on a previous check-up—if precognition is a side-ef-_ GAH! _"_ Gaster cried out as everything went white.

W.D. Gaster woke with a start. He stared in horror at his desk, papers in an arrangement they most certainly were not in second ago. Something was most assuredly _wrong_.

 **Line Break**

Papyrus eyed Grillby's with distaste, "Must we meet Father here?"

Sans snorted, "Where else are we supposed to eat lunch, bro?"

Papyrus groaned, "But it's so…so _greasy_ ," he shivered in disgust.

Sans smiled, "Hey, c'mon Papyrus, don't tell the prospective head of the Royal Guard is getting _cold_ feet".

Papyrus hung his head low, "If I'd known about all these puns I would have never agreed to move to Snowdin with you".

"Hey now, that's just _cold_ ".

"That's the exact same pun!"

"No it isn't," Sans shook his head with a mischievous smirk, "Context is completely different".

"…Let's just get inside," Papyrus grumbled.

When they entered the restaurant, the duo easily found Gaster, but not in a way they would have liked.

Their father looked tired and jumpy; muttering to himself and twitching erratically. His spare hands floated around him, rapidly writing down words, number letter, crossing the same things out—on sheets of paper and the surroundings.

Sans and Papyrus sidled into the booth across from him. "Father," Papyrus began, "Are you well?"

Sans smiled weakly, "Yeah, pops, you look like you've worked yourself down to the _bo_ -"

"Code RED"*

Papyrus and Sans's eye sockets widened. "What's wrong?,"* Papyrus asked shakily.

Gaster shook his head, "Not here, at my lab,"* that said, Gaster teleported away in a flash of purple light.

Sans and Papyrus sat in silence. After a moment, Papyrus put his hand on Sans's shoulder. He gulped, "We…we must not keep father waiting, Sans".

Sans nodded shakily, and he and his brother disappeared in a flash of blue light.

When they arrived at Gaster's lab, the brothers were shocked at the state of it. Papers and scraps of machinery were everywhere, Gaster's hands flying back and forth.

Gaster (when he finally noticed his sons) continued speaking in hands, "Good, nothing happened, yet, that's good, maybe this time…" he trailed off.

"Pops…" Sans said warily, "What's going on, and why are we still speaking in hands, isn't this place completely private".

Gaster giggled madly, "You would think so, but no, no, I don't know, I don't know," he pressed his hands against his face, his spare ones shaking erratically in the air, "IdontknowIdontknowIdontknowIdontknow…!" He rambled loudly.

"Father!" Papyrus ran up to Gaster, grabbing his arms, "Father, look at me!" Gaster stopped his mad mantra, "I…I don't know what's going on, but rest assured, Sans and I will help, or I am not Papyrus, the greatest guard to ever live!"

Gaster stared at Papyrus, then his lips curled into a small smile. One of his spare hands patting his youngest son on the head, "Thank you Papyrus…you always know what to say…always," Gaster frowned heavily, "always".

Sans walked over, placing a hand on Gaster's shoulder, "What's going on pops? What do you need?"

Gaster smiled once more, standing up, "Come with me, I'll explain on the way".

 **Line Break**

Gaster growled, "Is there no rhyme or reason to these-what did Sans call them-RESETS?"

He shifted his gaze to the clock, his eye-sockets widening slightly at the time, "They are late…very late…they've never been this late". Worry seized his SOUL, and he quickly teleported to their home in Snowdin.

"Sans…Papyrus!" He teleported here and there, calling out to his children.

"P-Pa-Papyrus…"

Gaster swiveled towards Sans voice. He ran forward. When his son came into view, he froze.

"Papyrus, n-no, please!" Sans lie in a heap, crying over the dusty remains of Papyrus's armor and scarf. "No…no goddammit!" Sans cried out.

Gaster fell on his knees, tears streaming down his face. What…what sort of…abomination…could even think to hurt, to kill, his son—the sweetest, most pure creature to ever grace the Underground?

He cried out to the heavens, his mournful howls mixing with Sans's, creating a cacophonous wail.

A few miles away, Flowey heard their cries. He grimaced, _"Maybe I shouldn't have killed all those monsters…all these damn cries are getting on my nerves"._

After what felt like hours, Gaster and Sans could no longer make a sound. Numbly, Gaster picked himself up, walking towards his remaining son. "Sans…Sans we have to go," he bent down to grab his son, but Sans swatted his hand away.

"G-go a-away".

"Sans," his hand was swatted away again, "Sans…" another swat.

Gaster bent down low, hugging Sans, and Papyrus's remains, close to him, "Shh…Don't worry son…This sin shall not go unpunished…I promise".

Gaster stood up, holding onto both Sans and Papyrus's clothes, his spare hands gathering the Dust. He teleported them to his house, where they could mourn in private.

 **Line Break**

Gaster slowly shuffled past the various monsters hiding in the lab. He didn't know how long he had spent with Sans, how many tears they had shed, but that was behind him. He now had one goal, one drive, a singular need. Gaster could feel his mad, wide smile crack his skull.

"Professor Gaster!" He schooled his face, turning to Alphys, who was shambling towards him.

"What is it Alphys?"

Alphys huffed and puffed, "I, uh, I n-need to talk to you".

Gaster frowned, looking clear path, "Now is not the time, I need to get the equipment, find the one who killed Pa-"

"That's the thing P-professor, I," she leaned up to whisper, "I th-think I know w-what's responsible f-for everything".

Gaster snapped his head towards Alphys. He roughly grabbed her by the shoulder, and teleported to the door to the lab. When they landed, a large group of monsters were shoved aside.

"Hey," one of them growled, "What's the bi-" he found himself staring into Gaster's eye sockets, blank, unending. He gulped, "…N-never mind".

Gaster merely turned towards a keypad, punched in his access code, and shoved Alphys inside when it opened.

He shut the door, "What do you know?"

Alphys pushed her hands together nervously, "W-well s-sir, the th-thing i-is, I, uh, I-"

"Spit it out!"

"It's my fault," Alphys cried, "Back when the K-K-King ordered us to experiment with DETERMINATION, after you declared it a failure, I-I-I went back and I got some test subjects. One of them w-was a flower that I injected with DETERMINATION. I thought it was a bust, so I m-moved on, but a lot of monsters said they found v-v-v-ines and flower p-pe-etals among Dust and I-urk!"

Alphys clawed desperately at Gaster's hand.

Gaster trembled, "You mean to tell me," his voice was cold as ice, "That, because you disobeyed a direct order, my son is dead?"

Alphys could not nothing but feebly nod through her choked sobs. Her eyes widened in fear as a large draconic skull appeared above Gaster. She resumed her struggles with fervor when a ball of purple energy grew within its open maw.

Gaster held up a hand, poised to snap. Yet, after the ball of energy expanded to full capacity, he didn't. Instead, he lowered his hand, sending the skull away. He released his grip on Alphys.

Her glared down at her shuddering form, "Rest assured, when this is all said and done, you will wish you had died with the others". He spun on his heel; teleporting away, leaving Alphys alone, her strangled cries her only companion.

 **Line Break**

Flowey sighed. It was, honestly, really boring without any monsters around. _"Isn't there at least one monster around who actually has something resembling a spine?"_

He continued his grumblings until he entered the hall, where he SAVED out of habit. He was surprised to see a tall, dark clothed figure standing halfway down it. Moving closer revealed it to be a figure he hadn't seen much, or at all really, in this or his previous life.

"Is this really Asgore's last line of defense?" he jeered. "Some scrawny scientist," Flowey scoffed, "I always knew the old goat was growing seni-!"

To Flowey's immense shock, a large skull appeared—out of nowhere! —In front of him, blasting him into oblivion.

Flowey jolted when he LOADED. _"…What the hell?!"_

 **Line Break**

Gaster almost laughed, he had forgotten all about the RESETS in light of recent events. He idly wondered if he would ever find the cause of them. He hung his head, he wondered if he would ever want to do anything after this.

Regardless, he would kill this flower, and then go back to Sans, and from there…

The flower came into sight once more, and Gaster wasted no time in blasting it. Then, to his surprise, the flower dove underneath the blast, "Wha-" following his instincts, Gaster sidestepped, dodging a salvo of bullets. He turned around, shooting dozens of bones at the flower. It weaved through a few, but ended up getting skewered.

Gaster found himself standing alone in the Hall once more. He narrowed his eye-sockets, "Could it be…?"

 **Line Break**

Flowey shook in rage. Time and time again, that damn skeleton found some way to kill him. And Flowey couldn't even say that he was giving as good as he got, because when he did manage to hit Gaster (which was an annoying rarity) the scientist's HP barely went down.

Flowey shifted his gaze to the RESET button. He scowled, but hit the button all the same.

 **Line Break**

Gaster jolted awake. He frantically looked around, _"Where?!...My lab…But that means…he RESET to…the beginning?...!"_ His eye-sockets widened, and he teleported to Snowdin.

He ran up to Sans and Papyrus's house, beating on the door rapidly. He stumbled slightly when the door swung open.

"Nyeh?…Father, what are you-huh!" Papyrus looked down at his father, who was kneeling, clutching onto Papyrus's legs. "Um, father…why are you crying, is something wrong?"

Gaster merely shook his head, smiling as tears slid down his face.

Papyrus heard a door slam open upstairs; "Sans" he turned around, "You're in a hurry…Do you know what's go-wah!" Papyrus fell to the floor as Sans jumped on his back.

Papyrus scrunched up his face his face at the sight of his father and brother, crying and hugging him fiercely, "…Did I make it into the Royal Guard?"

Sans wiped his eyes, chuckling as he did so, "No…I can't speak for pops, but I just really wanted to, I don't know, hug you".

Papyrus turned to Gaster expectantly.

Gaster smiled shakily, "Does a father need an excuse to be happy to see his children?"

Papyrus smiled, pulling them close, "No, I guess not".

They stayed there for several long minutes.

Gaster sighed deeply, basking in the moment, the peace, the relief. But…he still had something he needed to do.

 **Line Break**

Flowey shook some snow off of his petals. He always hated the first few steps out of the Ruins; one of the worst things about having a plant body was that the cold felt _really_ cold. He smirked, still, didn't mean it was without bene-

"So, you start out in the Ruins…"

Flowey froze, sweat pouring down his stem. Trembling, he turned around, to see the dark, imposing form of W.D. Gaster. Flowey stared slack-jawed. It was impossible! There was no way!

Gaster's eyes glowed dangerously, "Tell me…did you honestly believe that, by breaking Time and Space, you could erase your sins?"

Flowey immediately initiated a reset.

He appeared near the hole leading up to the Surface. He let out a sigh of relief. He'd just stay in the Ruins for a bit. After all, Toriel had the exit under lock and key, no one could get in or o-

"So, is this what you call a home?"

Flowey trembled once more.

Gaster smiled cruelly, "…You are going to have a _HELL_ of a time".

 **Line Break**

Sans frowned deeply. He really didn't know why he felt overjoyed to see Papyrus this morning. Although if he had to guess…No, he didn't want to follow that train of thought.

The phone rang, breaking him out of his introspection. He picked it up, "Hello?"

"Sans!" Sans winced at the loud cry.

"…What is it Alphys?"

"I-its your father! He's gone crazy!"

Sans snorted, "And here I thought you scientist types stuck together…I guess-"

"THIS ISN'T THE TIME FOR PUNS! I mean, you're father's following…something…and shooting lasers and teleporting and, and—did you know he could do all those things?"

"Alphys, calm down," Sans frowned heavily, "Where is Gaster now?"

 **Line Break**

Flowey didn't know how long this was going to last. He'd all but given up on RESETS (only bothering to use them when he found himself well and truly cornered).

He'd managed to lose Gaster when he entered Hotland. But Flowey knew this was only a temporary solution. Flowey started to think hard about how to fix this.

He remembered (from a past life) that Asgore mentioned the Core being one of the greatest and most powerful things to ever exist in the Underground.

Flowey grinned evilly.

"There you are!"

Flowey cried out, diving underground to avoid another blast.

 **Line Break**

Sans and Papyrus rushed towards Core room. They followed the sound of Gaster's blasters. After a particularly loud blast, the entire place shook.

Sans and Papyrus looked at each other, and moved at a greater pace.

They slammed open the doors to see Gaster frantically typing on several different computers.

"Pops!"

"Father!"

Gaster didn't turn around, "Sans, go to the third computer on the left! Input the SOL algorithm—I'll tell you what else to do after that! Papyrus, head over to the northern wall: if the lights flash red, pull the right most lever: blue, the middle and left most levers: and if it flashes yellow, pull all of them. Repeat this for every wall, now!"

Sans and Papyrus rushed off to do as told.

 **Line Break**

Gaster cursed. Even with all the counter-measures they activated, the Core was still in critical condition. He scowled; there was only one thing to do.

"Sans, Papyrus! Head for the machine!"

Papyrus opened the machine as Sans punched in a few codes. "All right Pops, I've got it up and running, what ne-!" Sans's eye widened in surprise when he was shoved into the machine. He and Papyrus stared wide-eyed as Gaster locked the machine.

"Pops! What are you doing Pops?!"

"Father? Father this doesn't seem like a good idea!"

Gaster smiled sadly, placing his hand on the window, before teleporting away.

"Pops?...Pops, this isn't funny! Pops!" Sans slammed on the window, "POPS!" he slammed against the window again.

The two brothers heard a small crack. Sans gazed fearfully at the glass, energy from the core seeping in.

His eye flashed, and a transparent shield formed around Papyrus as he covered the crack with his glowing hands. Then the Core exploded.

 **Line Break**

Sans woke with a start. He held his head in his hands, _"Ugh…what happened…! Pops!"_

Sans leapt out of bed. He rushed down the stairs, heading for Papyrus, who was in the kitchen. "Sans!" his brother chirped, "You're up early! Perhaps you would like to have some of my spaghetti!"

Sans stared slack-jawed, "…Papyrus, what are you doing?"

His brother frowned, "What does it look like I'm doing? I'm making spaghetti!"

"Why are you making spaghetti when the last time we saw Pops, he was caught in an explosion?!"

Papyrus stopped cooking, "Sans…who are you talking about?"

Sans stared hard, "Wh-what do you mean? W.D. Gaster, royal scientist, one of the oldest monsters to ever exist, our DAD?!"

Papyrus titled his head, "Sans, I'm sorry, but I honestly have no idea who you're talking about…Are you feeling alright?"

Sans stood stock-still, "…Nothing bro…Guess I'm just, uh, _dead_ tired".

 **Line Break**

Sans stared blankly at the machine that saved him and of the greatest things Gaster ever made (next to the Core and his brother) and now it was just…sitting there.

He'd talked with every monster Gaster knew personally.

Gerson, _"Sorry kiddo, never heard of any 'Gaster' fellow, and I'm the oldest monster in the Underground!"_

Alphys, _"S-Sans, I-I've been the R-Royal S-Scientist for, well, years n-now"._

Asgore gave a bit more of a reaction, but it was still a fruitless endeavor, _"I'm don't think that…no, I'm sure…I've not heard of a man named Gaster"._

Every trace of his father was gone. Photographs which he was prominently featured in were either heavily altered, or didn't exist anymore.

He looked down at the tear-stained, poorly hand-drawn picture he made, he grabbed a marker, and shakily wrote the words "don't forget".

He walked over to the machine, tearing off a piece of tape as he did so. He taped the picture to the machine, "Don't worry Pops, I'll save you…I promise".

 **A/N: And thus ends what may be my only foray into writing Undertale FanFiction. I can only hope it's decent. Be sure to leave a review. Later.**

 ***: These bits of text were supposed to be in Wingdings, but the doc manager's formatting kept on changing it. Oh well.**


End file.
